1. Field of the Invention
The present invention relates to a technique for visualizing an order of reading content contained in a structured document such as an HTML document. Particularly, the present invention relates to a technique that facilitates a check on the reading order.
2. Description of the Related Art
A text-to-speech application such as a screen reader or a voice browser reads content contained in a structured document such as an HTML document in an order set in a DOM (Document Object Model) tree. Thus, the content has to be written in an order based on the meanings (meaningful order) so as to be made easily understandable when being read. Such a requirement is mentioned also in Check Point 6.1 in Web Content Accessibility Guidelines 1.0 published as W3C (World Wide Web Consortium) recommendation.
The reading order of the content has been checked so far by the text-to-speed application such as the screen reader in order to check whether or not the content is written in a meaningful order.
One method for the checking is conversion into text. This checking method converts content into text such as: displaying source code of the HTML document; displaying the HTML document in a layout with a style sheet turned off; or displaying an output result from a tool that simulates a reading operation of a screen reader.
Another method is a checking method by displaying sequence numbers. This is a method in which an HTML document in the designed layout is displayed with sequence numbers in the reading order overlaid thereon (for example, refer to Kasday, L. R., “A Tool to Evaluate Universal Web Accessibility”, Proc. the 2000 Conference on Universal Usability (ACM), pp. 161-162, 2000).
There are also techniques for checking a reading position in an entire webpage. For example, Japanese Unexamined Patent Application Publication No. 2001-109612 discloses a technique of specifying information, by use of tags, for displaying a part within a specified range in a visually distinguished manner. This technique makes it possible to make settings such as displaying a range specified as a reading target with its background color, character color or character size changed from the other part, or displaying the range in a shaded manner. In addition, Japanese Unexamined Patent Application Publication No. 2006-171544 discloses a technique of presenting a reading position by making use of an audio attribute such as pitch, length, or strength of a voice. According to this technique, the audio attribute can be changed as the reading position proceeds from one to another. Japanese Unexamined Patent Application Publication No. 2005-010992 further discloses a technique aimed at enhancing a Webpage's function of transmitting information to a user. In this technique, a webpage is written, including descriptions with tags specifying texts to be read and the order of reading these texts.
In the checking method by conversion into text, however, it is difficult to comprehend a correspondence relationship between each of the content expressed in text and the content laid out by the style sheet. For this reason, the checking method by conversion into text involves a problem in that the checking requires a long time, and a problem that the method is not intuitive and therefore cannot be fully utilized by a beginner.
On the other hand, in the checking method by displaying the sequence numbers, the reading order can be accurately comprehended. However, in the checking method by displaying the sequence numbers, the sequence numbers have to be tracked one by one for comprehending a flow of the reading order of the content. For this reason, this checking method also requires a long time for comprehending local interchange of the sequence numbers and comprehending an entire flow of the reading order of the content.
Additionally, each of the techniques of Japanese Unexamined Patent Application Publication No. 2001-109612 and Japanese Unexamined Patent Application Publication No. 2006-171544 allows checking on a current reading position. Each of these techniques, however, does not allow checking on reading positions before and after the current reading position, such as reading positions immediately before and after the current reading position. For this reason, even the techniques of Japanese Unexamined Patent Application Publication No. 2001-109612 and Japanese Unexamined Patent Application Publication No. 2006-171544 have a problem of not enabling comprehension of an entire flow of the reading order of the content and of local interchange of sequence numbers in the order.
Moreover, the technique of Japanese Unexamined Patent Application Publication No. 2005-010992 makes it possible to read the content in a meaningful order even in a case where the content is not written in a meaningful order. However, this method requires a description specifying the reading order to be previously written in a structured document by use of tags. This method is therefore laborious. In addition, since there is a risk of there being a mistake in the specification of the reading order, the technique of Japanese Unexamined Patent Application Publication No. 2005-010992 cannot eliminate the need for checking whether the reading order is correctly specified.